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3 years ago

8

On a hot summer day, you need to leave your house for 30 minutes. To use the least amount of energy, should you turn off your ai

r conditioning system, turn up the thermostat, or leave it set at your normal temperature?

1 answer:

Kobotan [32]3 years ago

5 0

Leave it at your normal temperate, if you turn it off it'll take more energy for it to cool off when u get back home.

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The thermal transfer of energy by electromagnetic waves through the vacuum of space is called

Olenka [21]

Answer: Radiation

Explanation:

There are three ways in which the thermal transfer occurs:

1. By Conduction, when the transmission is by the <u>direct contact</u>.

2. By Convection, heat transfer <u>in fluids </u>(like water or the air, for example).

3. By Radiation, by the <u>electromagnetic waves</u> (they can travel through any medium and in <u>vacumm</u>)

So, in the outter space is vacuum, this means the energy cannot be transmitted by convection, nor conduction. It must be transmitted by electromagnetic waves that are able to travel with or without a medium, and this is called radiation.

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2 years ago

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A carpenter is driving a 15.0-g steel nail into a board. His 1.00-kg hammer is moving at 8.50 m/s when it strikes the nail. Half

bekas [8.4K]

Answer: The increase in temperature of the nail after the three blows is 8.0636 Kelvins. The correct option is (d).

Explanation:

Kinetic energy of the hammer ,K.E.=

$\frac{1}{2}mv^2=\frac{1}{2}1.00 kg\times (8.50 m/s)^2=36.125 J$

Half of the kinetic energy of the hammer is transformed into heat in the nail.

Energy transferred to the nail in one blow =

$\frac{1}{2}K.E.=\frac{1}{2}\times 36.125 J=18.0625 J$

Total energy transferred after 3 blows,Q = $3\times 18.0625 J=54.1875 J$

Mass of the nail = 15 g = 0.015 kg

Change in temperature = $\Delta T$

Specif heat of the steel = c = 448 J/kg K

$Q=mc\Delta T$

$54.1875 J=0.015 kg\times 448 J/kg K\times \Delta T$

$\Delta T=8.0636 K\approx 8.1 K$

The increase in temperature of the nail after the three blows is 8.1 Kelvins.Hence, correct option is (d).

4 0

2 years ago

1. In a(n) ______________________ circuit, all parts are connected one after another along one path.

poizon [28]

Answer:

1. A <em>series circuit </em>is a closed circuit which has all loads connected in a row and there is only one path for the current to flow.

2. The <em>Ohm's Law </em>state that a current flow through a resistor is directly proportional to the voltage across it $R = \frac{V}{I}$

3. A <em>parallel circuit </em>is a closed circuit divided into branches that it has two o more paths for the current to flow and the loads are parallel to each other which mean the voltage across them is the same for all loads.

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2 years ago

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I NEED THIS A SOON AS POSSIBLE

vivado [14]

Work is done when spring is extended or compressed. Elastic potential energy is stored in the spring. Provided inelastic deformation has not happened, the work done is equal to the elastic potential energy stored.

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2 years ago

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When Missourians carve their initials into the bark of a tree, the damage leaves the tree open to ____________________.

sasho [114]

Answer:

In fact, carving letters into a tree probably won't hurt it. ... In general, the tree will compartmentalize the wound and it will heal over. The initials that remain visible are essentially scar tissue, permanent scar tissue.

Explanation:

Unfortunately, when carving into the trunk of a tree the blade of a knife often penetrates the outer bark and cuts into the inner bark. ... In cases that the phloem is damaged all the way around the trunk (in a ring for example), the tree will slowly and eventually starve to death.

add my s n a p

luke_raines19

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2 years ago